.TH std::filesystem::space 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::filesystem::space \- std::filesystem::space

.SH Synopsis
   Defined in header <filesystem>
   std::filesystem::space_info space( const std::filesystem::path& p  \fB(1)\fP \fI(since C++17)\fP
   );
   std::filesystem::space_info space( const std::filesystem::path& p, \fB(2)\fP \fI(since C++17)\fP
                                      std::error_code& ec ) noexcept;

   Determines the information about the filesystem on which the pathname p is located,
   as if by POSIX statvfs.

   Populates and returns an object of type filesystem::space_info, set from the members
   of the POSIX struct statvfs as follows:

     * space_info.capacity is set as if by f_blocks * f_frsize.
     * space_info.free is set to f_bfree * f_frsize.
     * space_info.available is set to f_bavail * f_frsize.
     * Any member that could not be determined is set to
       static_cast<std::uintmax_t>(-1).

   The non-throwing overload sets all members to static_cast<std::uintmax_t>(-1) on
   error.

.SH Parameters

   p  - path to examine
   ec - out-parameter for error reporting in the non-throwing overload

.SH Return value

   The filesystem information (a filesystem::space_info object).

.SH Exceptions

   Any overload not marked noexcept may throw std::bad_alloc if memory allocation
   fails.

   1) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed
   with p as the first path argument and the OS error code as the error code argument.
   2) Sets a std::error_code& parameter to the OS API error code if an OS API call
   fails, and executes ec.clear() if no errors occur.

.SH Notes

   space_info.available may be less than space_info.free.

.SH Example


// Run this code

 #include <cstdint>
 #include <filesystem>
 #include <iostream>

 std::uintmax_t disk_usage_percent(const std::filesystem::space_info& si,
                                   bool is_privileged = false) noexcept
 {
     if (constexpr std::uintmax_t X(-1);
         si.capacity == 0 || si.free == 0 || si.available == 0 ||
         si.capacity == X || si.free == X || si.available == X
     )
         return 100;

     std::uintmax_t unused_space = si.free, capacity = si.capacity;
     if (!is_privileged)
     {
         const std::uintmax_t privileged_only_space = si.free - si.available;
         unused_space -= privileged_only_space;
         capacity -= privileged_only_space;
     }
     const std::uintmax_t used_space{capacity - unused_space};
     return 100 * used_space / capacity;
 }

 void print_disk_space_info(auto const& dirs, int width = 14)
 {
     (std::cout << std::left).imbue(std::locale("en_US.UTF-8"));

     for (const auto s : {"Capacity", "Free", "Available", "Use%", "Dir"})
         std::cout << "│ " << std::setw(width) << s << ' ';

     for (std::cout << '\\n'; auto const& dir : dirs)
     {
         std::error_code ec;
         const std::filesystem::space_info si = std::filesystem::space(dir, ec);
         for (auto x : {si.capacity, si.free, si.available, disk_usage_percent(si)})
             std::cout << "│ " << std::setw(width) << static_cast<std::intmax_t>(x) << ' ';
         std::cout << "│ " << dir << '\\n';
     }
 }

 int main()
 {
     const auto dirs = {"/dev/null", "/tmp", "/home", "/proc", "/null"};
     print_disk_space_info(dirs);
 }

.SH Possible output:

 │ Capacity       │ Free           │ Available      │ Use%           │ Dir
 │ 84,417,331,200 │ 42,732,986,368 │ 40,156,028,928 │ 50             │ /dev/null
 │ 84,417,331,200 │ 42,732,986,368 │ 40,156,028,928 │ 50             │ /tmp
 │ -1             │ -1             │ -1             │ 100            │ /home
 │ 0              │ 0              │ 0              │ 100            │ /proc
 │ -1             │ -1             │ -1             │ 100            │ /null

.SH See also

   space_info information about free and available space on the filesystem
   \fI(C++17)\fP    \fI(class)\fP
